Here’s the situation: • You’re downloading a huge list of data from iCloud. • You’re saving it one by one (sequentially) into SwiftData. • You don’t want the SwiftUI view to refresh until all the data is imported. • After all the import is finished, SwiftUI should show the new data. The Problem If you insert into the same ModelContext that SwiftUI’s @Environment(.modelContext) is watching, each insert may cause SwiftUI to start reloading immediately. That will make the UI feel slow, and glitchy, because SwiftUI will keep trying to re-render while you’re still importing. How to achieve this in Swift Data ?

I have an app which uses ubiquitous containers and files in them to share data between devices. It's a bit unusual in that it indexes files in directories the user grants access to, which may or may not exist on a second device - those files are identified by SHA-1 hash. So a second device scanning before iCloud data has fully sync'd can create duplicate references which lead to an unpleasant user experience. To solve this, I store a small binary index in the root of the ubiquitous file container of the shared data, containing all of the known hashes, and as the user proceeds through the onboarding process, a background thread is attempting to "prime" the ubiquitous container by calling FileManager.default.startDownloadingUbiquitousItemAt() for each expected folder and file in a sane order. This likely creates a situation not anticipated by the iOS/iCloud integration's design, as it means my app has a sort of precognition of files it should not yet know about. In the common case, it works, but there is a corner case where iCloud sync has just begun, and very, very little metadata is available (the common case, however, in an emulator), in which two issues come up: I/O may hang indefinitely, trying to read a file as it is arriving. This one I can work around by running the I/O in a thread created with the POSIX pthread_create and using pthread_cancel to kill it after a timeout. Attempts to call FileManager.default.startDownloadingUbiquitousItemAt() fails with an error Error Domain=NSCocoaErrorDomain Code=257 "The file couldn’t be opened because you don’t have permission to view it.". The permissions aspect of it is nonsense, but I can believe there's no applicable "sort of exists, sort of doesn't" error code to use and someone punted. The problem is that this same error will be thrown on any attempt to access that file for the life of the application - a restart is required to make it usable. Clearly, the error or the hallucinated permission failure is cached somewhere in the bowels of iOS's FileManager. I was hoping startAccessingSecurityScopedResource() would allow me to bypass such a cache, as it does with URL.resourceValues() returning stale file sizes and last modified times. But it does not. Is there some way to clear this state without popping up a UI with an Exit button (not exactly the desired iOS user experience)?

This simple test fails in my project. Similar code in my application also crashes. How do I debug the problem? What project settings are required. I have added SwiftData as a framework to test (and application) targets? Thanks, The problem is with: modelContext.insert(item) Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0) import XCTest import SwiftData @Model class FakeModel { var name: String init(name: String) { self.name = name } } @MainActor final class FakeModelTests: XCTestCase { var modelContext: ModelContext! override func setUp() { super.setUp() do { let container = try ModelContainer(for: FakeModel.self, configurations: ModelConfiguration(isStoredInMemoryOnly: true)) modelContext = container.mainContext } catch { XCTFail("Failed to create ModelContainer: \(error)") modelContext = nil } } func testSaveFetchDeleteFakeItem() { guard let modelContext = modelContext else { XCTFail("ModelContext must be initialized") return } let item = FakeModel(name: "Test") modelContext.insert(item) let fetchDescriptor = FetchDescriptor<FakeModel>() let items = try! modelContext.fetch(fetchDescriptor) XCTAssertEqual(items.count, 1) XCTAssertEqual(items.first?.name, "Test") modelContext.delete(item) let itemsAfterDelete = try! modelContext.fetch(fetchDescriptor) XCTAssertEqual(itemsAfterDelete.count, 0) } }

hi, in my app, i have created and pushed CKRecords to the public database. others using the app have pushed CKRecords as well. is there any way i can query iCloud for "all the CKRecords that i created?" thanks, DMG

Hi, I am currently experiencing some trouble when using parent model property in a predicate of a child model. I have an Item class that define parent-child relationship: @Model class Item { var timestamp: Date @Relationship(inverse: \Item.children) var parent: Item? var children: [Item] init(parent: Item? = nil, children: [Item] = [], timestamp: Date = .now) { self.parent = parent self.children = children self.timestamp = timestamp } } I subclass this model like that: @available(iOS 26, *) @Model final class CollectionItem: Item { /* ... */ } When i make a Query in my View like that the system crashes: @Query( filter: #Predicate<CollectionItem> { $0.parent == nil }, sort: \CollectionItem.name, ) private var collections: [CollectionItem] CrashReportError: Fatal Error in DataUtilities.swift AppName crashed due to fatalError in DataUtilities.swift at line 85. Couldn't find \CollectionItem.<computed 0x000000034005d4e8 (Optional<Item>)> on CollectionItem with fields [SwiftData.Schema.PropertyMetadata(name: "name", keypath: \CollectionItem.<computed 0x000000034003c120 (String)>, defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "icon", keypath: \CollectionItem.<computed 0x000000034003ca04 (Optional<String>)>, defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "timestamp", keypath: \Item.<computed 0x0000000340048018 (Date)>, defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "parent", keypath: \Item.<computed 0x0000000340048a4c (Optional<Item>)>, defaultValue: nil, metadata: Optional(Relationship - name: , options: [], valueType: Any, destination: , inverseName: nil, inverseKeypath: Optional(\Item.<computed 0x0000000340048fe8 (Array<Item>)>))), SwiftData.Schema.PropertyMetadata(name: "children", keypath: \Item.<computed 0x0000000340048fe8 (Array<Item>)>, defaultValue: nil, metadata: nil)] When I query as Item it works but then i cannot sort on CollectionItem field and must add unnecessary down casting: @Query( filter: #Predicate<Item> { $0.parent == nil && $0 is CollectionItem }, ) private var items: [Item] Am I missing something? Is it a platform limitation or a known issue?

Hi all, As you know, when using SwiftData Cloudkit, all relationships are required to be optional. In my app, which is a list app, I have a model class Project that contains an array of Subproject model objects. A Subproject also contains an array of another type of model class and this chain goes on and on. In this type of pattern, it becomes really taxxing to handle the optionals the correct way, i.e. unwrap them as late as possible and display an error to the user if unable to. It seems like most developers don't even bother, they just wrap the array in a computed property that returns an empty array if nil. I'm just wondering what is the recommended way by Apple to handle these optionals. I'm not really familiar with how the CloudKit backend works, but if you have a simple list app that only saves to the users private iCloud, can I just handwave the optionals like so many do? Is it only big data apps that need to worry? Or should we always strive to handle them the correct way? If that's the case, why does it seem like most people skip over them? Be great if an Apple engineer could weigh in.

My entity has a startDate (NSTime) attribute where I use the date and time in my detail display of the entity. And in my list, I need to group my entities by day (YYMMDD) based on the start date; and I want to ensure that it can adapt to the region where the user is currently (e.g. if user travels or migrate, the YYMMDD should be adapted based on the current region). Does Core Data SectionedFetchRequest supports strftime() functions from SQLite (https://sqlite.org/lang_datefunc.html) or what is an effective alternative sectioned fetch in my case?

If I use <FetchRequest.returnsDistinctResults> with unique "identifier" property, and there happened to be multiple NSManagedObjects in Core Data that contains the same "identifier", does the FetchRequest retrieve the latest modified/created object? Is there a way to define the <FetchRequest.returnsDistinctResults> logic to be based on another property (e.g. "creationDate" / "modifiedDate") and the ascension order?

Hi guys. Can someone please confirm this bug so I report it? The issue is that SwiftData relationships don't update the views in some specific situations on devices running iOS 18 Beta. One clear example is with CloudKit. I created a small example for testing. The following code creates two @models, one to store bands and another to store their records. The following code works with no issues. (You need to connect to a CloudKit container and test it on two devices) import SwiftUI import SwiftData struct ContentView: View { @Environment(\.modelContext) private var modelContext @Query private var records: [Record] var body: some View { NavigationStack { List(records) { record in VStack(alignment: .leading) { Text(record.title) Text(record.band?.name ?? "Undefined") } } .toolbar { ToolbarItem { Button("Add Record") { let randomNumber = Int.random(in: 1...100) let newBand = Band(name: "New Band \(randomNumber)", records: nil) modelContext.insert(newBand) let newRecord = Record(title: "New Record \(randomNumber)", band: newBand) modelContext.insert(newRecord) } } } } } } @Model final class Record { var title: String = "" var band: Band? init(title: String, band: Band?) { self.title = title self.band = band } } @Model final class Band { var name: String = "" var records: [Record]? init(name: String, records: [Record]?) { self.name = name self.records = records } } This view includes a button at the top to add a new record associated with a new band. The data appears on both devices, but if you include more views inside the List, the views on the second device are not updated to show the values of the relationships. For example, if you extract the row to a separate view, the second device shows the relationships as "Undefined". You can try the following code. struct ContentView: View { @Environment(\.modelContext) private var modelContext @Query private var records: [Record] var body: some View { NavigationStack { List { ForEach(records) { record in RecordRow(record: record) } } .toolbar { ToolbarItem { Button("Add Record") { let randomNumber = Int.random(in: 1...100) let newBand = Band(name: "New Band \(randomNumber)", records: nil) modelContext.insert(newBand) let newRecord = Record(title: "New Record \(randomNumber)", band: newBand) modelContext.insert(newRecord) } } } } } } struct RecordRow: View { let record: Record var body: some View { VStack(alignment: .leading) { Text(record.title) Text(record.band?.name ?? "Undefined") } } } Here I use a ForEach loop and move the row to a separate view. Now on the second device the relationships are nil, so the row shows the text "Undefined" instead of the name of the band. I attached an image from my iPad. I inserted all the information on my iPhone. The first three rows were inserted with the first view. But the last two rows were inserted after I extracted the rows to a separate view. Here you can see that the relationships are nil and therefore shown as "Undefined". The views are not updated to show the real value of the relationship. This example shows the issue with CloudKit, but this also happens locally in some situations. The system doesn't detect updates in relationships and therefore doesn't refresh the views. Please, let me know if you can reproduce the issue. I'm using Mac Sequoia 15.1, and two devices with iOS 18.0.

Hi everyone, Complete newbie here. Building an app and trying to use Cloudkit. I've added the CloudKit capability, triple checked the entitlements file for appropriate keys, made sure the code signing entitlements are pointing to the correct entitlements file. I've removed and cleared all of those settings and even created a new container as well as refreshed the signing. I just can't seem to figure out why I keep getting this error: Significant issue at CKContainer.m:747: In order to use CloudKit, your process must have a com.apple.developer.icloud-services entitlement. The value of this entitlement must be an array that includes the string "CloudKit" or "CloudKit-Anonymous". Any guidance is greatly appreciated.

HI, swiftdata is new to me and any help would be appreciated. In my swiftui app I have a functionality that reinstates the database from an archive. I first move the three database files (database.store datebase.store-wal and database.store-shm) to a new name (.tmp added for backup incase) and then copy the Archived three files to the same location. the move creates the following errors: " BUG IN CLIENT OF libsqlite3.dylib: database integrity compromised by API violation: vnode renamed while in use: /private/var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store.tmp invalidated open fd: 4 (0x20)" I get the same message in console for all three files. then I reinitialise the model container and get no errors as my code below .... let schema = Schema([....my different models are here]) let config = ModelConfiguration("database", schema: schema) do { // Recreate the container with the same store URL let container = try ModelContainer(for: schema, configurations: config) print("ModelContainer reinitialized successfully!") } catch { print("Failed to reinitialize ModelContainer: (error)") } } I get the success message but when I leave the view (backup-restore view) to the main view I get: CoreData: error: (6922) I/O error for database at /var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store. SQLite error code:6922, 'disk I/O error' and error: SQLCore dispatchRequest: exception handling request: &lt;NSSQLFetchRequestContext: 0x302920460&gt; , I/O error for database at /var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store. SQLite error code:6922, 'disk I/O error' with userInfo of { NSFilePath = "/var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store"; NSSQLiteErrorDomain = 6922; } error: -executeRequest: encountered exception = I/O error for database at /var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store. SQLite error code:6922, 'disk I/O error' with userInfo = { NSFilePath = "/var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store"; NSSQLiteErrorDomain = 6922; } CoreData: error: SQLCore dispatchRequest: exception handling request: &lt;NSSQLFetchRequestContext: 0x302920460&gt; , I/O error for database at /var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store. SQLite error code:6922, 'disk I/O error' with userInfo of { NSFilePath = "/var/mobile/Containers/Data/Application/499A6802-02E5-4547-83C4-88389AEA50F5/Library/Application Support/database.store"; NSSQLiteErrorDomain = 6922; } Can anyone let me know how I should go about this - reseting the database from old backup files by copying over them. or if there is a way to stop the database and restart it with the new files in swiftdata my app is an ios app for phone and ipad

Problem Description: When a device (Device 2) stays offline for an extended period after a record is deleted from another synced device (Device 1) via CloudKit, is it possible for Device 2 to miss the deletion notification when it reconnects, even when using CKSyncEngine? This scenario raises questions about whether CKSyncEngine can reliably sync changes if CloudKit archives or purges metadata related to deletions during the offline period. Steps to Reproduce: At time t0: · Device 1 and Device 2 sync successfully via CKSyncEngine (shared record RecordA). Device 2 goes offline. On Device 1: · Delete RecordA; sync completes via CKSyncEngine. Wait for a duration potentially exceeding CloudKit’s change retention window (if such a window exists). Bring Device 2 back online. Observe synchronization: · Expected Behavior: CKSyncEngine removes RecordA from Device 2. · Observed Behavior: RecordA remains on Device 2. Key Questions: Under these conditions, can Device 2 permanently miss the deletion event due to CloudKit’s internal metadata management? Is there a documented retention policy for CloudKit’s change history, and how does CKSyncEngine handle scenarios where this history is truncated? What is the recommended pattern to ensure no events are missed, regardless of offline duration? Clarifications Needed: · If CloudKit does discard deletion metadata after a period, is this considered a framework limitation, or should developers implement additional safeguards? · Does CKSyncEngine log warnings or errors when it detects incomplete sync histories? Environment: · CKSyncEngine with SQLite · CloudKit Private Database · iOS/macOS latest versions Thank you for clarifying how CKSyncEngine is designed to handle this edge case!

Hi everyone, On macOS 26.4 beta (with Xcode 26.4 beta), I’m seeing the following console messages in a brand new SwiftData + CloudKit template project (no custom logic added, fresh CloudKit container): updateTaskRequest called for a pre-running task com.apple.coredata.cloudkit.activity.export.F9EE783D-7521-4EC2-B42C-9FD1F29BA5C4 updateTaskRequest called for an already running/updated task com.apple.coredata.cloudkit.activity.export.F9EE783D-7521-4EC2-B42C-9FD1F29BA5C4 Error updating background task request: Error Domain=BGSystemTaskSchedulerErrorDomain Code=8 "(null)" These messages appear: When CloudKit is enabled Occasionally on app launch Often when bringing the app back to the foreground (Cmd-Tab away and back) Even with zero additional SwiftData logic They do not appear when CloudKit is disabled. This behavior is reproducible on a completely new project with a fresh CloudKit container. Questions: What exactly do these messages indicate? Is BGSystemTaskScheduler Code=8 expected in this context? Are these safe to ignore? Is this a known change in logging behavior in macOS 26.4 beta? Additionally, in a larger project I’ve observed SwiftData crashes and initially suspected these logs might be related. However, since the issue reproduces in a fresh template project, I’m unsure whether this is simply verbose beta logging or something more serious. Any clarification would be appreciated. Filed as FB21993521.

I'm running into an undocumented error coming back from CloudKit operations. Specifically, I'm attempting to save new records via CKModifyRecordsOperation. I'm receiving this error for each of the records in the perRecordSaveBlock callback: &lt;CKError 0x3018ac3c0: "Internal Error" (1/3001); "MMCSEngineCreate failed"&gt; Is anyone else facing this error? It has been happening for several days and I'm finally getting around to reproduction with the Console app and logs. I have 16 records on my device locally that each one gets this error back. FB16547732 - CloudKit: CKModifyRecordsOperation saving new records results in Error &lt;CKError 0x3018ac1e0: "Internal Error" (1/3001); "MMCSEngineCreate failed"&gt;

Some users of my app are reporting total loss of data while using the app. This is happening specifically when they enable iCloud sync. I am doing following private func setupContainer(enableICloud: Bool) { container = NSPersistentCloudKitContainer(name: "") container.viewContext.automaticallyMergesChangesFromParent = true container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy guard let description: NSPersistentStoreDescription = container.persistentStoreDescriptions.first else { fatalError() } description.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey) description.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey) if enableICloud == false { description.cloudKitContainerOptions = nil } container.loadPersistentStores { description, error in if let error { // Handle error } } } When user clicks on Toggle to enable/disable iCloud sync I just set the description.cloudKitContainerOptions to nil and then user is asked to restart the app. Apart from that I periodically run the clear history func deleteTransactionHistory() { let sevenDaysAgo = Calendar.current.date(byAdding: .day, value: -7, to: Date())! let purgeHistoryRequest = NSPersistentHistoryChangeRequest.deleteHistory(before: sevenDaysAgo) let backgroundContext = container.newBackgroundContext() backgroundContext.performAndWait { try! backgroundContext.execute(purgeHistoryRequest) } }

Does the CloudKit participant limit of 100 include the owner?

Hi, I have developed a calendar app with swiftData. I have set it to sync iCloud. When testing it, it seems that everything is fine. But after it's released, today, I uninstalled it and reinstalled it again. And I found that iCloud hasn't sync with local swiftData for six days. I have lost six days agenda and relevant information. I have checked the document, and it's said that there is no method to force to sync with iCloud. How to solve the issue? I think that the users can't forgive that it hasn't synced for six days. Best Wishes,

As of 2025-05-03, when a macOS user enables iCloud Drive synchronization for Desktop &amp; Documents in US region, does iCloud filter xattrs upon upload or later when downloading back to another macOS host? Or is it the case that iCloud has no filtering of third-party xattrs? Where can I find the technical document outlining exactly what iCloud does with xattrs set on macOS host files and folders synchronized with iCloud Drive?

anyone getting the following error with CloudKit+CoreData on iOS16 RC? delete/resintall app, delete user CloudKit data and reset of environment don't fix. [error] error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate _requestAbortedNotInitialized:](2044): <NSCloudKitMirroringDelegate: 0x2816f89a0> - Never successfully initialized and cannot execute request '<NSCloudKitMirroringImportRequest: 0x283abfa00> 41E6B8D6-08C7-4C73-A718-71291DFA67E4' due to error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)}

I have a model with a FamilyActivitySelection, currently i'm using a codable struct to store it with UserDefaults, but would prefer strongly to transition to Swift Data